Phase 1 Desktop Study

We provide quick, cost effective Phase 1 Desktop Study and Site Investigation services. Our phase 1 reports are designed to meet the needs of planning conditions and can provide an assessment of risks prior to property and land purchase.

A desktop study/phase 1 investigation is always required when dealing with a contaminated land planning condition. A desktop study can save money by identifying potential contaminated land issues at an early stage. This allows us to identify the most appropriate method for dealing with these risks. This is always the first stage of any contaminated land soil survey and is carried out before any soil sampling is carried out.

Guidance on contaminated land can be found here.

The technical guidance on risk assessment (CLR11) is available from here.

There is also useful guidance on development of housing on contaminated land from NHBC.

What is a Desktop Study?

A desktop study is the first part of the site investigation process. It involves a desk based collation of documentary data.  This includes records of site history, geology, hydrogeology/hydrology, waste,  pollution incidents etc. to produce an outline conceptual model. In other words, a desktop study refers to an investigation that is carried out purely by desk based research. No sampling of soils is carried out at this stage. The desktop study may also be referred to as: a desk study, phase 1 assessment, phase 1 site assessment , phase 1 investigation, phase 1 site investigation,  Preliminary Risk Assessment (PRA)  preliminary investigation,  soil survey,  site survey etc.

A  phase 1 investigation should comprise of both the desktop study itself and a site reconnaissance (also known as a walkover survey). The latter allows a visual inspection to be made of both the site and the surrounding area.  No samples are taken up at this stage.

The information is combined to produce a Conceptual Site Model. An explanation can be found here, but in essence it is used to explain how a given contaminant  may interact with site users or the wider environment. This allows the degree of risk to be determined. This in turn establishes what, if any, further action may be required.


This guidance states that all contaminated land site investigations must be carried out in a phased manner.

This means that all site investigations should initially begin with a desktop study also known as a phase 1 investigation. This will use existing data and possibly information gained from a visual site inspection (walkover survey) to allow a preliminary risk assessment to be carried out. If no risk from contamination in soils to site users or the wider environment, then no further action should be required.

Should a potential risk be identified, then an intrusive investigation (or phase 2 investigation) will be required to establish the likelihood and extent of the risk. This can use a number of different methods from hand sampling though to drilling of boreholes with wells installed and must be based on the scope identified in the desk top study. It enables soils (and sometimes rocks) to be sampled and submitted for analysis. This is the stage that is generally thought of when people think of site investigations and may be referred to as soil sampling, a soil survey, soil testing etc. This may also be combined with a geotechnical investigation that allows data to be gathered on soil strength parameters to enable foundation design. The data gathered will be used to refine the conceptual model and risk assessment to establish whether a risk is present.

About our Desktop Study Services:

  • They are designed to meet the requirements of the regulators
  • They are detailed and specific to your site
  • Are quick, cost effective and fixed price
  • We never recommend unnecessary further work and if further work is required, you have no obligation to use us
  • We have substantial experience of liaising with the regulators on behalf of our clients.
In many cases where the previous site usage has had a low impact a phase 1 investigation is sufficient to discharge the contaminated land planning conditions.

We will liaise with the regulators on your behalf to quickly address any concerns that they may have at no additional cost!